triSlvF.f

C  @file      triSolve.f
C  @Author    Mitch Richling<http://www.mitchr.me/>
C  @Copyright Copyright 2006 by Mitch Richling.  All rights reserved.
C  @breif     Simple example illustrating strsv from BLAS.@EOL
C  @Keywords  blas lapack netlib fortran linear system algebra
C  @Std       F77 MIL-STD-1753
C  @Notes     How to solve a triangular system.  BLAS supports upper and
C             lower triangular systems, the matrix being transposed, and
C             the diagonal being unitary or not.  This program
C             illustrates the most common case when the matrix is upper
C             triangular and has non-units on the diagonal.

      program trislv

      implicit none

      real m(5,5)
      real x(5)

      external strsv

      external sgeprt

      data m/3, 0, 0, 0, 0,
     *       5, 8, 0, 0, 0,
     *       7, 1, 5, 0, 0,
     *       9, 4, 9, 4, 0,
     *       1, 7, 3, 9, 5/

      data x/1, 2, 3, 4, 5/

      call sgeprt(5, 5, m, 'm=')
      call sgeprt(1, 5, x, 'x=')

      !          UPLO, TRANS, DIAG, N, A, LDA, X, INCX )
      call strsv('U', 'N',    'N',  5, m, 5,   x, 1 )

      call sgeprt(5, 5, m, 'm=')
      call sgeprt(1, 5, x, 'x=')

      end